Method of forming piles



March 21, 1967 B. A. LAMBERTON METHOD OF FORMING FILES Filed Sept. 5,1964 FIG. I

INVENTOR. BRUCE A. LAMBERTON ATTORNEYS United States Patent Ofi icePatented Mar. 21, 1967 3,309,878 NIETHGD 0F FORMING FILES Bruce A.Lamberton, Berea, Ohio, assignor, by mesne assignments, to ConstructionTechniques, Inc., Cleveland, Ohio, a corporation of Delaware Filed Sept.3, 1964, Ser. No. 394,189 5 Claims. (Cl. 6153.62)

This invention pertains to the art of concrete structures and moreparticularly to concrete structures having metallic reinforcing ortensioning members embedded therein.

The invention is particularly applicable to sub-earthsurface concretestructures of the type which are formed in situ, that is, where theconcrete is placed in the earth in a plastic state and there allowed toharden, and will be described with particular reference thereto,although it will be appreciated that the invention has broaderapplications.

A number of different methods are known for forming sub-earth-surfaceconcrete structures in situ, namely: by excavating either with orwithout a form and pouring concrete into the excavated space; byrotating an anger into the earth to the desired depth and thereafterwithdrawing the auger without rotation while simultaneously pumping aconcrete under pressure into the space formed by the withdrawal of theanger as is taught in US. Patent No. 2,729,067, issued January 3, 1956,and assigned to the assignee of this application; or by rotating a toolhaving sidewardly projecting mixing arms into the earth whilesimultaneously forcing a concrete under pressure into the earth inadvance of the rotating tool whereby to mix the concrete and the earthinto a homogeneous mixture as is taught in US. Patent No. 2,782,605,issued Feb. 26, 1957, also assigned to the assignee of this application.

All of such concrete structures, when the concrete hardens, haveexcellent downward or load bearing characteristics because such forcesplace the concrete under compression where, as is known, it has itsmaximum strength.

Difiiculty has been experienced in the past, however, with such concretestructures when called upon to resist uplift forces or bending forces.Such forces result in small cracks developing in the concrete thuspermitting the entrance of ground Water and the resultant corrosion ofthe metal tie rods or reinforcing bars.

Uplift forces are normally transferred to the structure by means of ametallic tie-rod embedded either in the upper end of or throughout theentire vertical height of the structure. The structure then transfersthe uplift forces to the surrounding soil supposedly in a uniformlydistributed manner. However, it has been found that because of thegreater rigidity of the concrete relative to the metal tie-rod, theseuplift forces are transferred to the concrete structure at orimmediately adjacent to the upper point of fastening of the tie-rodthereto. The concrete, which is weak in tension, tends to develop smallcracks progressively downward under high uplift forces to relieve thetension and the tie-rod progressively transfers the uplift forces to theconcrete at lower and lower points in the structure. However, the smallcracks which develop permit the entrance of ground water and theexposure of the tie-rod to corrosion. As the tie-rod is the onlyeffective material in the pile resisting the uplift forces, this attackcan be of a very serious nature.

A further cause of these tensions is the location of the principalpoints of resistance of the soil to these uplift forces. Thus the upliftforces create shearing forces in the surrounding soil. The resistance ofthe soil to the shearing forces depends on the friction between theadjacent soil particles, which friction increases with depth in the soilbecause of the increased pressure between the particles. The soil has amaximum resistance to the uplift forces at the lower end of thestructure.

When an ordinary reinforced concrete structure is initially pulledupwardly, it stretches, and in doing so transfers the forces to andshears the soil at the upper end where the soil is weakest. As the pullincreases, the stretching continues and the transfer occursprogressively deeper into the soil. However, eventually the soil in theupper layers fails due to movement of the upper end of the structurebeyond the ability of the soil to resist. Also, where the soil has notsheared, part of the Weight on the soil below has been lessened causinglower frictional resistance between the particles, and thus a lesserresistance to shearing forces at or adjacent to the lower end of thestructure. In any event, the tendency is for the entire structure to bein tension with the principal transfer of forces to the soil ultimatelybeing at or adjacent the lower end.

The present invention contemplates an arrangement which overcomes all ofthe above-referred to difficulties, and provides for applying the upliftforces to the concrete structure at or adjacent to its lower end only,means being provided for insuring that the tie-rod may stretch and movelongitudinally more or less freely relative to the structure above thepoint of fastening.

Where the concrete structures are called upon to resist lateral orbending forces, the side of the structure is placed in tension. Toresist such tension forces, it has been conventional in the past toembed metallic reinforcing members within the structure while theconcrete is still plastic. This tension member is provided with meansfor rigidly fastening itself or preventing longitudinal movement thereofrelative to the concrete after the concrete hardens. With such anarrangement, because the tension member has a greater elasticity thanthe concrete, it does not begin to accept its portion of the load forcesuntil usually the concrete has been stressed beyond its breaking point.Again small tension cracks develop in the heavily loaded areas of theconcrete making the tension member accessible to attack by corrosiveelements.

The present invention contemplates a concrete structure which can beformed in situ, which avoids all of the above referred to difficulties,and others, which has a maximum strength for a given amount of materialagainst forces in all directions and which can be quickly, easily, andeconomically put into place.

In accordance with the broadest aspect of the invention, a verticallyelongated plastic concrete structure is formed having a metallic tie-rodextending longitudinally therethrough, such tie-rod having anchor meansat its lower end for rigidly fastening it to the concrete and meansabove the lower end for permitting free longitudinal movement of the rodrelative to the concrete structure after the concrete has hardened. Withsuch an arrangement, all of the uplift forces are transmitted to theconcrete structure at the lower end thereof and portions above the pointof force transmittal are placed under compression rather than tension asheretofore. Furthermore, the forces are transmitted to the concretestructure at points below the earth surface where the soil is morecompact and has a greater shear resistance and a much greater ability toresist the uplift forces.

Further, in accordance with the invention, after the concrete hashardened, the tie-rod is placed under tension by exerting an upliftforce on the upper end thereof, and such upper end is then rigidlyfastened to the upper end of the concrete structure. The tie-rod isunder tension and the concrete structure is under a permanent state ofcompression. Thus, bending forces on the concrete structure must firstneutralize the compression forces in the concrete before tension forcesare developed, thus giving to the concrete structure a substantiallyincreased resistance against lateral bending forces.

Further in accordance with the invention, the tie-rod may be locatedcloser to the side of the concrete structure on which the bendingtension forces will exist whereby to place this side of the structureunder a greater state of compression than the opposite side. Thus aninitial camber may in some instances be introduced into the concretestructure in a direction towards the bending forces.

The principal object of the invention is the provision of a new andimproved method of placing sub-earth-surface concrete structure whichwill have a maximum resistance against uplift or lateral forces.

Another object of the invention is the provision of a new and improvedmethod for forming sub-earth-surface concrete structures in situ havingtension members extending therethrough which enables the structure whenconcrete structure which will have a maximum resistance against upliftor lateral forces.

Another object of the invention is the provision of a new and improvedmethod of placing sub-earth-surf-ace concrete structures formed in situunder compression or for transmitting uplift forces to the lower endthereof.

The invention may take physical form in certain parts and arrangementsof parts and certain steps and combinations of steps, preferredembodiments of which will be described in detail in this specificationand illustrated in the accompanying drawing which is a part hereof andwherein,

FIGURE 1 is a cross-sectional view of the earths surface showing aconcrete structure formed in situ and illustrating a preferredembodiment of the invention for transmitting uplift forces to the lowerend of the structure;

FIGUR-E l-a is a cross-sectional view of FIGURE 1 taken from the linelal-a thereof;

FIGURE 2 is a view somewhat similar to FIGURE 1 illustrating analternative embodiment of the invention wherein the tension member isplaced under a permanent state of tension;

FIGURE 3 is a still further alternative embodiment of the inventionshowing an alternative way of placing the concrete structure; and,

FIGURE 4 is a partial cross-sectional view ilustrating a furthermodification of the present invention.

Referring now to the drawings wherein the showings are for the purposeof illustrating preferred embodiments of the invention only, and not forthe purpose of limiting same, FIGURE 1 shows a cross section of theearth-surface 9 having extending vertically downwardly therein aconcrete structure it) formed in situ which in turn has a tie-rod 11extending from a point adjacent the lower end to a point above the upperend of the structure 10. In accordance with one aspect of the invention,the concrete structure 10 is formed by a method shown in United StatesPatent No. 2,729,607 wherein an auger-type drill is sunk into the earthto define the location and depth of a cavity for the structure withoutremoving the earth therefrom, and then a fiuid hydraulic cement grout isforced into the cavity under suflicient force to fill the cavity as theanger is removed.

The earths surface 9 may be of any known characteristic including sand,clay, rock, or a mixture of one or all three, the only requirement beingthat it be of a nature such that the concrete structure may be formed insitu by any known method.

The concrete structure 10 may have any desired vertical height, anydesired horizontal width, thickness or cross-sectional shape and may beformed in any manner such that the concrete when placed in the soil 9 isin a plastic state and is allowed to harden in the soil.

In this respect, concrete as used throughout the specification andclaims, is made up of a mixture of a liquid vehicle, a cementitiousmaterial and usually, but not necessarily, one or more granularmaterials. The granular materials may include without limitation, soil,sand, fiy ash or gravel, rock or aggregate of any desired size. Thecementitious material may be any of the known cementitious materialssuch as without limitation, Portland cement or the like which when mixedwith or suspended in the liquid vehicle and upon being allowed to standor cool, or both, will harden and bind the granular material, if any,into a solid rigid body. The liquid vehicle may be of a type such thatwhen mixed with the cementitious material employed will either evaporateor combine with the cementitious material to leave the cementitiousmaterial in a hardened state which wiil bind the granular material intoa solid rigid body.

The concrete unles otherwise stated, may be either in the plastic orhardened state, it being understood that plastic concrete when allowedto stand for periods of time which may be referred to as the hardeningtime will change to the hardened state.

The term vertical as used throughout the specification and claims isused in the broader sense of being in any direction leading below theearths surface as fitting within the sense of the particularrequirements of the concrete structure being installed.

By the term in situ is meant the forming of the concrete structure froma plastic concrete present in the ultimate position of use of thestructure, the concrete being allowed to harden prior to the placing ofloads thereon.

The concrete structure 10 is in accordance with the invention, formed insitu in any known or desired manner. Prefer-ably, however, the concretewhile in the plastic state is placed under hydraulic pressure so that aplurality of tiny fingers or protrusions 12 extend laterally into thesoil 9 beyond the actual limits of the structure 10 itself. Preferablythe structure 10 is formed-as is taught in U.S. Patent No. 2,729,067issued Jan. 3, 1956, or U.S. Patent No. 2,782,605 issued Feb. 26, 1957,and both assigned to the 'assignee of this application. In the first ofthese patents an auger having a hollow shaft is screwed into the soil tothe depth desired by the ultimate structure. The auger is then graduallywithdrawn without rotating while simultaneously concrete is pumped underpressure through the hollow shaft to the lower end of the auger, theconcrete under pressure forcing itself laterally into the soil 9 to formthe fingers 12. In such case the concrete as desired is mixed above thesurface of the earth and is pumped through the shaft.

In the second mentioned patent, a hollow shaft having sidewardlyprojecting mixing arms is rotated vertically into the earth whilesimultaneously forcing concrete under pressure into the earth in advanceof the mixing arms. Normally the concrete contains larger amounts ofliquid vehicles than is normal and the arms, as the tool is advancedinto the earth, mix the soil with the concrete. The tool is advanced tothe desired depth of the concrete structure and is then withdrawn whilecontinuing the rotation. The result is a thoroughly mixed sub-surfacestructure comprised of a mixture of concrete and the soil 9. In thisinstance it will be noted that the granular material or at least some ofit, is actually the soil. The concrete, however, which is forced throughthe hollow shaft under pressure, forces itself laterally into crevicesin the soil 9 to form the fingers 12.

In a still further alternative arrangement for forming the concretestructure 10 in situ, a cavity may be formed under the earths surface tothe desired depth either with or without the use of form members toprevent the sides of the cavity from collapsing. Assuming that forms areemployed, concrete is poured into the cavity, the forms are partiallywithdrawn and known methods of ramming the upper surface of the concreteare employed for the purpose of creating hydraulic pressures thereonwhich will force the concrete into the crevices of the soil 9 for thepurposes of forming the fingers 12.

In any event, it will be seen that a concrete structure is formed belowthe surface of the earth which because of the laterally protrudingfingers 12 will have a maximum area of cont-act with the soil 9 in orderthat a maximum resistance of vertical movement either upwardly ordownwardly of the concrete structure 10 can be developed for a givenvertical dimension and for a given characteristic of soil 9.

Also, it should be understood that the concrete structure or column 10may extend to any desired height above the upper surface of the soil 9.The above-ground portion of the concrete column 10 may be formed by anysuitable method. The rod member 11 is anchored at its lower end in theconcrete column 10 as in the previously described embodiments. Above itslower end the rod member 11 is freely movable longitudinally withrespect to the concrete column 10. The upper end of the rod member 11 issubjected to tension forces. Preferably, the rod member 11 is placedunder tension after the concrete column 10 has hardened and the upperend of the rod member 11 is rigidly fastened, such as to the upper endof the concrete column 19 or to a structure which the concrete column 19supports above ground, such as a bridge beam. Due to suchpost-tensioning of the rod member 11, the concrete column 10 is therebyplaced under compression.

This enables the column to withstand greater lateral or bending stressesbecause such initial compression of the concrete column, due to thetension on the rod member 11, must first be overcome before any portionof the column can go into tension. This makes the present inventionparticularly advantageous for bridge columns which are subjected to suchshear and bending forces.

In FIGURE 1, immediately following the formation of the plastic concretestructure 19, the tension rod 11 is inserted therein in accordance withthe invention.

In FIGURE 1, the tie rod 11 has anchor means at the lower end which inthe preferred embodiment consist of a cone-nut 20 rigidly fastened as bywelding to the lower end of the member 11. A plurality ofcircumferentially spaced anchor rods 21 extend outwardly and upwardlyfrom the cone 20, the maximum radial spacing of the upper ends 22 of thearms being generally just less than the maximum diameter or thickness ofthe concrete structure 10. With this arrangement when the concrete is ina plastic state, the tie rod 11 with the anchor means at the lower endcan be forced longitudinally through the structure 10 so that theanchoring means are located adjacent the lower end of the structure 10and by virtue of the radial spacing of the ends 22 the lower end of themember 11 will be generally equally spaced from the sides of thestructure it). After the concrete hardens, the anchor means will berigidly fastened to the structure 10.

Further in accordance with the invention, means are provided whereby thetension member 11 above the anchor means may move longitudinallyrelative to the structure 19. While such result may be accomplished in anumber of different Ways, in the preferred embodiment of the invention,an elongated sleeve 25 is placed coaxially about the tension member 11.to form a space 26 therebetween sealed at the lower end against theingress of concrete by a sealing means 27 and having a length such thatwhen the tension member 11 is placed in position as shown, the sleevewill extend preferably above the upper surface 28 of the concretestructure it). In this way it will be appreciated that the surfaces ofthe tension member 11 above the sealing means 27 are free from anyfastening to the concrete structure It) and thus tension forces on thetension member 11 result in an elongation thereof unimpeded by the morerigid and nonelastic adjacent concrete structure. All of the tensionforces on the tension member 11 are transmitted to the lower end of theconcrete structure 10.

The sleeve 25 may be of any desired material which will prevent theconcrete from coming into physical and immovable contact with thesurfaces of the tension memher 11 above the anchor means shown. Thesleeve 25 may thus be of steel, paper, or in some cases, may evenconsist of a thin plastic layer of material such as grease or bituminouspreparations which will prevent the adherence of the concrete to the rod11.

In the event that a steel or paper sleeve is employed where an actualphysical space 26 does exist, a plastic compound may be poured into thespace subsequent to the final installation to prevent the entrance ofmoisture thereinto.

Thus in the embodiment shown the concrete structure 10 is formed eitherby casting in place as is described in Patent No. 2,729,067 or mixed inplace as is described in Patent No. 2,782,605. After the withdrawal ofthe tool in either case, the tension member 11 with its outersurrounding sleeve 25 and its anchor means at the lower end are thenforced longitudinally through the still plastic concrete and theconcrete is then allowed to harden.

Thereafter uplift forces on the member 11 are transmitted directly tothe bottom of the structure 10 and the concrete in response to suchuplift forces is placed under compression throughout its entire length.

It will be appreciated that if desired the member 11 may be offset fromthe midcenter of the concrete structure 10, such arrangement beingaccomplished generally by varying the radial spacing of the ends 22 ofthe arms 21 from the centerline of the rod 11. Furthermore if desired,the axis of the rod 11 may extend at an angle relative to thelongitudinal axis of the structure 10.

It will futher be appreciated that one or a plurality of rods 11 may bedisposed within the concrete structure 10 particularly if the concretestructure 10 has either a very substantial diameter or if it has a verysubstantial thickness in one horizontal direction, thus in effectforming a wall beneath the surface.

It will also be appreciated that a plurality of cylindrical concretestructures 10 can be provided either tangentially touching one relativeto the other or overlap-ping each other to provide a continuous wall oftangent cylindrical concrete structures.

FIGURE 2 shows an alternative embodiment of the invention particularlyadapted to where the concrete structure must resist unidirectionalhorizontal forces such as where the earth 9 is removed from one sideafter the concrete structure is placed in position. In the embodimentshown in FIGURE 2 where like characters are employed to indicate likemembers corresponding to those of FIGURE 1 and similar characters areindicated with the same number with a prime mark added, the soil 9' isshown as flush with the upper surface 28 of the concrete structure if onthe left hand side while the opposite or right hand side either has allor some of the soil excavated or removed at least partially below theupper surface 28. The result is that the concrete structure 10 issubjected to substantial horizontal forces 30 toward the right whichforces will, as is conventional, tend to exert a bending action on theconcrete structure 10 and place the left hand surface thereof intension.

In accordance with the invention, however, the tierod 11 after beingplaced as described with reference to the embodiment of FIGURE 1 andafter the concrete has had a chance to fully harden, is placed undertension by any suitable means such as a jack, not shown, resting on theupper surface 28 and secured to the projecting end 32 which jack whenextended, places the rod member 11 under tension, such tension beingresisted by placing the concrete structure 10 into a state ofcompression. Thereafter the upper end of the rod member 11 is rigidlysecured or fastened at least to the upper end of the concrete structureit Such securing may be done in a number of different ways, but inthejpreferred embodiment an end anchor plate 35 is positioned to bearagainst the upper surface 28 of the concrete structure 10 and is securedto the rod member 11 by means of a wedge 36. Such a fastening means maybe employed alone; however,

in accordance with the preferred embodiment, concrete 37 is pumped intothe space 26 which concrete, when it hardens, acts as a bond between therod 11 and the sleeve 25, which sleeve in turn is secured to theconcrete structure 10. If desired, the anchor 35 may then be removed orleft in place.

Depending upon the amount of tensioning of the rod member 11, theconcrete structure will be placed in a corresponding amount ofcompression. Thus initial forces 30 on the concrete structure 10 willhave to neutralize the compression forces in the concrete before theconcrete goes into tension. It will thus be appreciated thatsubstantially greater forces can be withstood by the structure 10 thanwithout the post-tensioning operation.

Obviously and desirably, with such a posttensioning, the rod member 11will be located toward the side of the structure which will normally gointo tension when resisting the horizontal forces. With such anarrangement when the rod member 11 is pulled into tension, the concretestructure 10 will develop a slight camber or curve toward the directionof the force which must be resisted. It will thus be seen that thecamber of the structure must be completely neutralized before theconcrete will go into the undesirable tension state. Also a verysubstantial portion of the stresses will be taken up by the rod member11. Thus in FIGURE 2 the arms 21' on the left diverge less than the arms21 on the right to give such a spacing.

It will be appreciated that the arrangement shown may be used to resistnot only horizontal forces as above described, but also, andsimultaneously, load bearing forces as well as uplift forces,particularly if the concrete 37 is not employed for the purpose offilling the space 26. Thus uplift forces would result in an increasedtensioning on the member 11, all of which would be transmitted to thelower end of the structure 10, resulting in the structure 10 beingplaced in a further state of compression. Load bearing would betransmitted directly to the upper surface 28 without releasing thetension in the member 11.

It will be appreciated that in all instances the concrete structure 10has been shown as extending to the upper surface of the soil 9.Obviously this is not necessary and the upper surface 28 may terminateat any point below the upper surface of the soil 9. Furthermore, theconcrete structure 10 need not be continuous under the surface of thesoil.

FIGURE 3 shows the invention as applied to a more conventional way offorming sub-surface concrete structures than that above described. Thuswith the embodiment of FIGURE 3, a cavity 40 is formed in the soildefined by a casing 41. A rod member 11 having an anchor plate 42 weldedto the lower end thereof and a protecting coaxial sleeve sealed at itslower end to the rod 11 by means of packing 27, is positioned within thecavity with the anchor plate 42 preferably spaced slightly from thelower end of the cavity 40. Concrete 45 is then poured into the lowerend of the cavity 40 to a desired depth. The casing 41 is then removedto a point adjacent the upper end of the concrete 45. Thereafter heavyweights 46 suspended by cables 47 are dropped into the cavity 40 in sucha manner as to strike the upper surface of the concrete 45 while it isstill in a plastic state. The weights are then lifted by the cables 47and again dropped. This operation continues repetitively in order todrive the concrete 45 radially outwardly into the cracks and fissures ofthe soil to form the fingers 12 as above described. Thereafter theweights 46 are removed, more concrete is poured into the opening, thecasing 41 further removed and the operation continued until the entireconcrete structure is completed.

The concrete is then allowed to harden and the rod member 11 is placedunder tension as described with reference to the embodiment of FIGURE 1.

Referring now to FIGURE 4, the member 11 is pro- 8 vided with a lowerspiralled blade 50 so that the member 11 may be easily inserted into thestructure 10 by rotating the member. Consequently less force is requiredthan is required when the member must be forced downwardly into theunsolidified concrete of structure 10.

It will be appreciated that any of the processes for forming theconcrete structures may be so modified as to form a continuous wallbelow the surface of the earth 9.

The invention has been described with reference to preferred embodimentsonly. Obviously modifications and alterations will occur to others upona reading and understanding of this specification and it is my intentionto include all such modifications and alterations insofar as they comewithin the scope of the appended claims.

Having thus described my invention, I claim:

1. A method of forming a one-piece concrete pile formed in situextending below the earths surface and adapted to withstand upliftforces, comprising the steps of forming a substantially vertical hole inthe earths surface With an upper opening, inserting a reinforcing rodwith a body portion and a lower anchor means into said hole with saidanchor means near the bottom of said hole, said rod having a protectivesleeve extending from a po sition near said anchor to a position abovethe upper opening of said hole for preventing said concrete mixture fromcontacting said body portion of said reinforcing rod along a substantialportion of the length thereof, filling said hole with a plastic,hardenable concrete mixture, causing a hydraulic pressure on saidmixture to force said mixture outwardly into said earth, allowing saidconcrete mixture to harden to form a concrete pile having an upper and alower portion, supporting a rod receiving member near the upper portionof said concrete pile, placing said reinforcing rod under tensionbetween said rod receiving member and said lower anchor means, andsecuring said rod in a tensioned condition so the complete length ofsaid concrete pile between said upper and lower portions is compressed.

2. A method of forming in situ a one-piece concrete pile extending belowthe earths surface and adapted to withstand uplift forces, comprisingthe steps of forming a substantially vertical hole in the earthssurface, filling said hole with a plastic, hardenable concrete mixture,providing a reinforcing rod having a body portion and a lower anchor,securing a protective sleeve around said body portion and extending froma position near said lower anchor to a point substantially above saidanchor, fluid sealing said sleeve from said position to said point,inserting said reinforcing rod and sleeve into said concrete mixturebefore said concrete mixture hardens with said anchor near the bottom ofsaid hole and said point above the top of the concrete mixture wherebysaid sealed sleeve prevents the concrete mixture from contacting saidrod from said position to said point, allowing said concrete to hardento form a concrete pile having an upper and a lower portion, supportinga rod receiving member near the upper portion of said concrete pile,placing said reinforcing rod-under tension between said rod receivingmember and said lower portion of said concrete pile, and securing saidrod in its tensioned condition so the complete length of said concretepile between said upper and lower portion is compressed.

3. A method of forming a one-piece concrete pile formed in situextending below the earths surface and adapted to withstand upliftforces, comprising the steps of rotating an auger drill into the earthto the desired depth of said pile to form a cavity, forcing a fluidhydraulic cement grout into said cavity, below said drill and at asufficient pressure to fill said cavity as said drill is removed,removing said drill, before said grout hardens, inserting a reinforcingrod with a body portion and a lower anchor means into said cavity withsaid anchor means near the bottom of said cavity, preventing said groutfrom contacting said body portion of said reinforcing rod along asubstantial portion of the length of said concrete pile whereby the rodis spaced from said grout from a position adjacent said anchor means tothe top of said pile, allowing said cement grout to harden to form aconcrete pile having an upper and a lower portion, supporting a rodreceiving member near the upper portion of said concrete pile, placingsaid reinforcing rod under tension between said rod receiving member andsaid lower anchor means, and securing said rod in a tension condition sothe complete length of said concrete pile between said upper and lowerportions is compressed.

4. A method of forming a one-piece concrete pile formed in situextending below the earths surface and adapted to Withstand upliftforces, comprising the steps of rotating an auger drill into the earthto the desired depth of said pile to form a cavity, forcing a fluidhydraulic cement grout into said cavity, below said drill and at asufiicient pressure to fill said cavity as said drill is removed,removing said drill, before said grout hardens, rotating a reinforcingrod with a body portion and a lower spiral blade into said cavity withsaid spiral blade pulling said rod into said grout until said blade isnear the bottom of said cavity, preventing said grout from contactingsaid body portion of said reinforcing rod along a substantial portion ofthe length of said concrete pile whereby the rod is spaced from saidgrout from a position adjacent said spiral blade to the top of saidpile, allowing said cement grout to harden to form a concrete pilehaving an upper and a lower portion, supporting a rod receiving membernear the upper portion of said concrete pile, placing said reinforcingrod under tension between said rod receiving member and said lowerspiral blade, and securing said rod in a tension condition so thecomplete length of said concrete pile between said upper and lowerportions is compressed.

5. A method of forming a one-piece concrete pile formed in situextending below the earths surface and adapted to withstand upliftforces, comprising the steps of rotating an auger drill into the earthto the desired depth of said pile to form a cavity, forcing a fluidhydraulic cement grout into said cavity, below said drill and at asufiicient pressure to fill said cavity as said drill is removed,removing said drill, providing a reinforcing rod with a lower anchormeans, a body portion having a shielding structure over a substantiallength thereof and extending from a position adjacent said anchor meansto a position at the top of said rod, before said grout hardens,inserting said reinforcing rod into said cavity with said anchor meansnear the bottom of said cavity whereby the reinforcing rod is spacedfrom said grout by said shielding structure from a position adjacentsaid anchor means to the top of said pile, allowing said cement grout toharden to form a concrete pile having an upper and a lower portion,supporting a rod receiving member near the upper portion of saidconcrete pile, placing said reinforcing rod under tension between saidrod receiving member and said lower anchor means, and securing said rodin a tension condition so the complete length of said concrete pilebetween said upper and lower portions is compressed.

References Cited by the Examiner UNITED STATES PATENTS 1,805,265 5/1931Taussig 6l-53.62 3,114,245 12/1963 Jennings et a1. 6153.62

FOREIGN PATENTS 862,914 3/ 1961 Great Britain. 568,343 12/ 1956 Italy.

76,799 12/ 1954 Netherlands.

ROBERT F. WHITE, Primary Examiner.

J. A. FINLAYSON, Assistant Examiner.

1. A METHOD OF FORMING A ONE-PIECE CONCRETE PILE FORMED IN SITUEXTENDING BELOW THE EARTH''S SURFACE AND ADAPTED TO WITHSTAND UPLIFTFORCES, COMPRISING THE STEPS OF FORMING A SUBSTANTIALLY VERTICAL HOLE INTHE EARTH''S SURFACE WITH AN UPPER OPENING, INSERTING A REINFORCING RODWITH A BODY PORTION AND A LOWER ANCHOR MEANS INTO SAID HOLE WITH SAIDANCHOR MEANS NEAR THE BOTTOM OF SAID HOLE, SAID ROD HAVING A PROTECTIVESLEEVE EXTENDING FROM A POSITION NEAR SAID ANCHOR TO A POSITION ABOVETHE UPPER OPENING OF SAID HOLE FOR PREVENTING SAID CONCRETE MIXTURE FROMCONTACTING SAID BODY PORTION OF SAID REINFORCING ROD ALONG A SUBSTANTIALPORTION OF THE LENGTH THEREOF, FILLING SAID HOLE WITH A PLASTIC,HARDENABLE CONCRETE MIXTURE, CAUSING A HYDRAULIC PRESSURE ON SAIDMIXTURE TO FORCE SAID MIXTURE OUTWARDLY INTO SAID EARTH, ALLOWING SAIDCONCRETE MIXTURE TO HARDEN TO FORM A CONCRETE PILE HAVING AN UPPER AND ALOWER PORTION, SUPPORTING A ROD RECEIVING MEMBER NEAR THE UPPER PORTIONOF SAID CONCRETE PILE, PLACING SAID REINFORCING ROD UNDER TENSIONBETWEEN SAID ROD RECEIVING MEMBER AND SAID LOWER ANCHOR MEANS, ANDSECURING SAID ROD IN A TENSIONED CONDITION SO THE COMPLETE LENGTH OFSAID CONCRETE PILE BETWEEN SAID UPPER AND LOWER PORTIONS IS COMPRESSED.